Weight Loss Injections in the UK

Dr. Babak Ashrafi

Medically reviewed by

Dr Babak Ashrafi

Last reviewed: 07 Feb 2024

Weight loss injections are prescription weight loss medications that you usually inject into your abdomen, thigh or upper arm. These injections work by controlling your appetite, and help you lose weight by reducing the amount of food you need to eat to feel full.

The only weight loss injections currently licensed in the UK are Wegovy, Saxenda and Mounjaro, but there are a number of other injections that may help with weight loss that are not yet available or licensed in the UK and that may be available later.

If you want information about our weight loss service, please visit our Weight Loss FAQ page. Here, we cover questions about our weight loss programmes and provide additional information on our medications, side effects and ordering processes.

Two weight loss injection pens in blue and white

What are the different types of weight loss injections?

Wegovy (Semaglutide)

Wegovy is an injection for weight loss that contains an active ingredient called semaglutide, which is a medication that mimics a naturally occurring hormone produced in the intestines called glucagon-like peptide-1 (GLP-1). This hormone helps you regulate your appetite, and tells your brain you’re full up, so you find it easier to eat less. Wegovy is a highly effective medication for weight loss, and can help you lose up to 16% or more of your starting body weight. Wegovy is injected once per week.

Do weight loss injections hurt?

Dr Babak Ashrafi

Dr Babak Ashrafi

Although there is a little pain involved with self-injecting weight loss treatments, it is not the same as having an injection for a vaccination for example. Weight loss injection pens use a smaller needle and only need to inject below the skin and not into muscle tissue, like vaccinations do.” – Dr Babak Ashrafi, MBBS BSc - Clinical Lead for Service Development at ZAVA.

Mounjaro (Tirzepatide)

Mounjaro is an injection taken once per week that contains the active ingredient tirzepatide. Tirzepatide is a long-acting GIP receptor (glucose-dependent insulinotropic polypeptide receptor) and GLP-1 receptor agonist (glucagon-like peptide-1 receptor agonist). That means it

  • increases the secretion of insulin and your body’s sensitivity to it
  • suppresses the secretion of glucagon, a hormone increasing blood sugar,
  • suppresses appetite, and
  • slows gastric emptying.

Mounjaro is usually used to treat type 2 diabetes. It has recently been approved for weight loss in the UK, and can be prescribed online by our doctors.

Saxenda (Liraglutide)

Saxenda is a weight loss injection that works similarly to Wegovy. Saxenda contains the active ingredient liraglutide, which also behaves like the hormone GLP-1 and works by affecting the areas in your brain that control appetite. This makes you less hungry, so you can eat less. It is injected once a day.

Ozempic (Semaglutide)

Ozempic is a prescription injection for those with type 2 diabetes which helps to regulate your blood sugar level. It uses the same active ingredient as Wegovy (semaglutide), but it is only approved for type 2 diabetes and not as a weight loss treatment. It is also prescribed at a lower dosage, so it is less effective as a weight loss medication for most people than Wegovy.

Victoza (Liraglutide)

Victoza is a prescription anti-diabetic injection that contains the same active ingredient as Saxenda (liraglutide). Victoza is only prescribed for type 2 diabetes, and is not available as a treatment for weight loss.

Zepbound (Tirzepatide)

Zepbound is a prescription injection that contains the active ingredient tirzepatide, the same as Mounjaro. Zepbound and Mounjaro are effectively the same medication: Zepbound is approved for weight loss treatment in other countries, while Mounjaro is approved for type 2 diabetes and weight loss in the UK. Mounjaro helps you lose weight similarly to Wegovy and Saxenda, by reducing your appetite and helping you eat less.

Comparing weight loss injections

While there is no best weight loss injection for everyone, many people can find one that suits them. Choosing a weight loss injection can be tricky but some can be slightly more effective than others.

weight loss injections table

How do weight loss injections work?

Injections for weight loss contain ingredients that belong to a family of medications called GLP-1 agonists, which replicate the effects of a naturally occurring hormone called glucagon-like peptide-1 (GLP-1). This hormone helps to regulate your blood sugar levels, and also affects parts of your brain that control your appetite. This is why these medications that are prescribed for type 2 diabetes can also be effective for weight loss.

Weight loss injections are appetite suppressants, which mean that they work by reducing your appetite, so you do not need to eat as much to feel full and satisfied after a meal. It also helps reduce the likelihood you will snack in between meals, as you will feel fuller. This helps you to reduce your caloric intake, as you are eating less.

What happens when you stop taking weight loss injections?

When you stop taking weight loss injections you will not immediately regain all of the weight you lost, but you may experience an increase in appetite and weight gain. This is because the medication will stop reducing your appetite, so you may find yourself eating more food. It is important to keep up with regular exercise, dieting and any other complementary lifestyle changes you’ve made to assist your weight loss journey to make sure you keep the weight off.

Efficacy and benefits of weight loss injections

Weight loss injections are highly effective medications that can make your weight loss journey a lot easier. They are typically prescribed to people who struggle to lose weight through lifestyle changes alone, such as dieting and exercise.

The benefits of weight loss injections include:

  • feeling fuller for longer
  • the body converting sugar to energy more efficiently
  • lower blood sugar levels
  • a minimally invasive treatment (compared to surgery)
  • more effective results (compared to weight loss tablets or no treatment)

How effective are weight loss injections?

The weight loss injection Wegovy can help you to lose around 15% of your weight after 68 weeks, of using 2.4mg per week. Mounjaro is reported to be able to help you lose 22.5% body weight on average after 72 weeks of using 15mg per week (Source: emc). Weight loss injections are also usually well-tolerated by those who take them, with more than 80% of those taking 2.4mg Wegovy reporting weight loss of at least 5% of their initial body weight.

Weight loss injections only work as part of a weight management plan that includes diet and exercise.

Weight loss injections vs pills

Weight loss injection pens and pills are both effective for helping you lose weight, especially alongside a weight loss plan that includes complementary lifestyle changes. However, the right one for you will depend on your individual preferences, medical history, and whether these treatments are safe and appropriate for you.

How to take them

Weight loss pens are usually injected into your abdomen, thigh, or upper arm. Some people may find that injections are uncomfortable for them, especially daily injections.

Weight loss pills are swallowed 2-3 times per day, usually after each major meal. This can be a lot more convenient for people who struggle with injections.

How they work

Weight loss injections work by suppressing your appetite, reducing your caloric intake as you have to eat less food to feel full.

Not all weight loss pills work the same. The most common weight loss pills (orlistat and Xenical) work by reducing the amount of fat your body absorbs from food, passing it through your stool as waste. Some weight loss pills (Mysimba) are also appetite suppressants.


Weight loss injections typically lead to a higher amount of weight loss, compared to weight loss pills. Weight loss injections also tend to work faster, with weight loss results being seen more quickly than with pills.

Are weight loss injections safer than pills?

Both weight loss injections and pills are safe to use if prescribed by a doctor, and are designed to be used over a long period of time. Neither is necessarily “safer” than the other. A doctor will only prescribe these medications if they are considered to be safe and appropriate for you based on your medical history, and regular check ups can help you manage or prevent side effects.

How much do weight loss injections cost?

Weight loss injection prices will vary depending on how you purchase them. If prescribed on the NHS through their specialist weight loss services they may only cost the standard prescription charge.

If you buy weight loss injections online, then prices may vary based on what’s included in the service you’re buying through.

Name Price for 4 week course


From £179


From £57


From £189

Do weight loss injections work for everyone?

While weight loss injections are highly effective in supporting many people’s weight loss journeys, injections are not right for everyone. Weight loss injections are only suitable for overweight people, with a BMI over 30 or a BMI over 27 with weight-related health issues such as high blood pressure or type 2 diabetes.

Weight loss injections are usually well tolerated by most people. Studies have shown that Wegovy led to weight loss of at least 5% body weight in over 80% of those taking it (2.4mg weekly for 72 weeks), while 63.5% of people taking Saxenda successfully lost at least 5% weight (3mg daily for 56 weeks). This means that, for most people, weight loss injections work.

At ZAVA, our doctors will make sure that any weight loss injections will only be prescribed if it is determined they are safe and appropriate for you. This decision will be based on an assessment of your medical history by doctors who are licensed to practise in the UK.

Diabetes injections for weight loss

Diabetes injections, especially those that belong to a family of medications called GLP-1 agonists, have also been found to be effective weight loss medications.

These injections help to regulate blood sugar levels by mimicking a hormone called glucagon-like peptide-1 (GLP-1), and work by increasing the amount of insulin produced in your pancreas, and decreasing the amount of glucose produced in your liver. These medications have the added benefit of helping people lose weight by reducing their appetite and making them feel fuller after a meal. This makes weight loss injections a good choice for people with type 2 diabetes who are also overweight.

While the active ingredients are the same, diabetes injections are not typically prescribed only for weight loss. Injections such as liraglutide and semaglutide, which are typically prescribed for type 2 diabetes under the names Victoza and Ozempic, have also been prescribed at higher dosages for weight loss under the names Saxenda and Wegovy.

Safety and side effects of weight loss injections

Common side effects of weight loss injections

  • diarrhoea or constipation
  • nausea or vomiting (feeling or being sick)
  • headaches
  • dizziness
  • low blood sugar
  • dry mouth
  • redness or itching at injection site

Serious weight loss injection side effects

Stop using weight loss injections and contact a doctor if you experience any of the following:

  • severe stomach pain that doesn’t go away, even if you throw up
  • signs of gallbladder problems, including pain in the upper abdomen, fever, yellow skin or eyes, or clay-coloured poo
  • signs of low blood sugar, which includes dizziness or feeling light-headed, confusion, sweating, shakiness, blurred vision, anxiety, or a faster heartbeat.
  • kidney problems
  • changes to your eyesight
  • depression or suicidal thoughts

Most common side effects of weight loss injections are mild, and usually get better or go away completely after a few weeks of starting treatment.

Who shouldn’t take weight loss injections?

Weight loss injections aren’t right for everybody, and in some cases they may be unsafe depending on medications you are taking or pre-existing conditions.

Weight loss injections may not be recommended for:

  • people taking certain medications, such as diabetes medicines (including insulin) and immunosuppressants
  • pregnant or breastfeeding women
  • those with pancreatic disorders, such as pancreatitis
  • those with a history of thyroid cancer
  • those with a history of gallbladder disease

You should speak to your doctor about these conditions or medications before taking any weight loss injection.

What are the long term effects of weight loss injections?

Weight loss injections are designed to be used over a long period of time, typically ranging from 1 to 3 year courses. For most people, weight loss injections have no long term side effects and are safe weight loss medications. In some cases, long term effects of weight loss injections can include:

  • lower function of thyroid gland
  • problems with the pancreas, including pancreatitis
  • nausea
  • lower appetite

Where can I buy weight loss injections in the UK?

How to buy weight loss injections online?

You can order weight loss injections online from online doctor services like ZAVA. If you are overweight, you can request medications such as Wegovy through our online doctor service. Fill in a short online assessment about your health and our doctors will offer a prescription if the treatment is suitable for you. This treatment will be delivered directly to your door.

Can you get weight loss injections on the NHS?

Yes, weight loss injections such as Wegovy and Saxenda are available on the NHS. You may need to get an appointment with a weight management specialist first, and weight loss injections will usually only be prescribed if:

  • you’ve tried weight loss without medication first
  • you’ve tried treatments like orlistat first
  • weight loss surgery isn’t possible for you
  • you have a BMI of between 30 kg/m² and 35 kg/m² and a health problem that can affect your weight, such as diabetes
  • you have a BMI of 35 kg/m² or more, even if you do not have a weight related medical condition

Can you get weight loss injections over-the-counter?

No, you cannot get injections for weight loss over-the-counter, weight loss treatment must be prescribed to you by a doctor. A doctor needs to make sure it is safe to take weight loss medication before you are prescribed it.

What to expect during prescription weight loss injections treatment with ZAVA?

The process for getting weight loss injections with ZAVA is safe and convenient. All you need to do is complete a short online assessment, where you will answer questions about your health and medical history. Our doctors will make sure that it is safe and appropriate to prescribe treatment to you, and then your medication will be sent to an address of your choice in the post. You will also be sent detailed instructions on how to take your medication, and our doctors are available for any follow up questions via our encrypted messaging tool in your patient account.

When it is time to start a new course of your medication, you will complete a shorter assessment to provide an update on your health to make sure the medication is working effectively for you.

Our service includes a free support package designed by our in-house nutritionist and ongoing care in the form of free follow-up check ins with our doctors.

Weight loss injections reviews

  • Saxenda has a score of 7.5 out of 10 on drugs.com, based on user reviews. 66% of reviewers reported a positive experience, while 15% reported a negative experience. Reasons for negative Saxenda experiences include side effects such as gastrointestinal problems and negative impacts on mental health.
  • Wegovy has a score of 7.1 out of 10 on drugs.com, based on user reviews. 61% of reviewers reported a positive experience, while 21% reported a negative experience. Reasons for negative Wegovy experiences include side effects such as nausea, constipation, and other stomach issues.
  • Mounjaro for weight loss has a score of 8.9 out of 10 on drugs.com, based on user reviews. 84% of reviewers reported a positive experience, while 5% reported a negative experience. Reasons for negative Mounjaro experiences include side effects such as nausea, diarrhoea and weakness.

Conclusion: How to choose a weight loss injection?

Weight loss injections are safe and effective medications for most people. They can help you lose up to 20% or more of your starting weight, and can be effective for over 80% of people. The choice between Wegovy, Mounjaro and Saxenda will depend on your medical history, how often you’re comfortable injecting yourself, and what a doctor recommends. Wegovy and Mounjaro are a better choice for most people, as studies have shown they are more effective for weight loss and they are a weekly injection instead of a daily one.

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Frequently asked questions

How much weight can I lose with weight loss injections?

Most people will be able to lose at least 5% of their starting weight and many will be able to lose 15% or more. Some studies have shown weight loss of 20% or over.

How much weight you lose will depend on personal factors like your starting weight and metabolism. To give yourself the best chance of reaching your weight loss goal, you need to stick to your diet and exercise plan.

How long does it take for weight loss injections to work?

You may notice a change to your appetite after your first dose. Most people will notice a reduced appetite within the first few weeks. Weight loss itself will take longer to become noticeable. Around 12 weeks you should notice some weight loss but it takes longer for the full effect of treatment to be seen. Many studies check for results after 68 weeks of treatment.

Do I need to exercise while taking weight loss injections?

Yes, exercise is an important part of weight loss injection treatment. Weight loss injections don’t work by themselves, they need to be used alongside a diet and exercise plan.

Can you drink alcohol on weight loss injections?

Yes, but there are some considerations. Alcohol can lower your blood sugar which can make side effects of weight loss injections worse. Alcohol also contains a lot of calories and can lead to binge drinking. It’s generally a good idea to minimise alcohol intake during treatment.

Can weight loss injections be self-administered at home?

Weight loss injections are generally self-injected. The pens are used at home and you don’t need to see a doctor in person for each injection. A doctor will give guidance on how to self-inject and your medication will come with detailed advice too.

How much weight will come back after you stop taking weight loss injections?

There is no guarantee any weight will come back after you stop treatment. If you stick to your diet and exercise plan, you may not see any weight gain after stopping and you may even continue to see weight loss. If you don’t stick to your diet and exercise plan after stopping treatment your weight may go up again.

Who should not take semaglutide and other active ingredients?

People can’t take GLP-1 agonists like semaglutide and other weight loss injections if they have existing health conditions that make them unsafe, like heart failure or pancreatitis.

Medically reviewed by:
Dr Babak Ashrafi Clinical Lead for Service Expansion
Accreditations: BSc, MBBS, MRCGP (2008)

Babak studied medicine at King’s College London and graduated in 2003, having also gained a bachelor’s degree in Physiology during his time there. He completed his general practice (GP) training in East London, where he worked for a number of years as a partner at a large inner-city GP practice. He completed the Royal College of GPs membership exam in 2007.

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Last reviewed: 07 Feb 2024

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